The prior art is replete with various systems which operate to monitor patients for providing patient data to a central location. Such systems can be bedside systems whereby the patient is confined to a bed and is suitably connected to sensors so that physiological medical information is transmitted to a central location by means of cables or other means. Such systems are employed in the intensive care units (ICU) of hospitals where vital signs such as temperature, respiration, heart rate and so on of a patient are monitored.
Some modern techniques utilize wireless transmission, such as telemetry systems, whereby a patient is furnished with a transmitter and receiver. Sensors placed on the patient monitor electrical signals produced by the patient to provide e.g., EKG signals. These signals are then converted to other signals which can be transmitted by antennas, conventional radio links or by other radio frequency (RF) techniques. Existing ambulatory systems can provide various signals relating to the monitoring of e.g., the patient's temperature, heart rate and so on. Essentially, the type of medical data which can be transmitted by such systems includes any type of data which can be measured by conventional sensors which are applied to the skin or otherwise implanted in the patient. There are systems which also will give an indication of the location of the patient.
A typical prior art system is described in U.S. Pat. No. 4,958,645 entitled MULTI-CHANNEL DIGITAL MEDICAL TELEMETRY SYSTEM, which issued on Sep. 25, 1990 to Theodore E. Cadell et al. and is assigned to CME Telemetrix, Inc. of Canada. The medical radio telemetry system described therein utilizes a plurality of antennas which are distributed throughout a hospital or other premises. The patient is outfitted with a radio receiver and transmitter which unit is operative to collect data such as temperature, heart rate, pacer rate, respiration rate, brain activity level and blood pressure level. The transmitter and receiver associated with the patient operates in conjunction with one or more room locator transmitters. The room locator transmitters are spaced in rooms or about the area where the patient is being monitored. The signal from the patient's transmitter is passed to the room transmitters. All signals received by the patient are transmitted to an antenna system that is connected to a receiver. As indicated there is one or more antenna systems with means for switching between the systems to obtain the best signal. In the system, the patient also receives a signal from any one of the room locator transmitters and the patients unit transmits the received signal together with his EKG signal.
The transmitting antenna system transmits the signals to the receiving antenna which is connected to a receiver whereby the patient can be monitored at a remote location such as a central nursing location in a hospital. In this manner, all data which is being provided by the patient is transmitted to the central location and the data is transmitted together with a location signal received by the patient's receiver module. Thus, the location of the patient is known because the patient receives a location signal which is transmitted by the patient. Thus, the system enables the hospital staff to monitor patients and in the event of a particular medical problem the patient's position is immediately ascertained as well. There are other systems which monitor the status of the patient utilizing networking techniques.
U.S. Pat. No. 4,981,141 entitled WIRELESS ELECTROCARDIOGRAPHIC MONITORING SYSTEM issued on Jan. 1, 1991 to J. Segalowitz. This patent describes a stationary electrocardiographic monitoring system where the patient's heart-signaling sensing electrodes are each coupled to the heart-signal monitor/recorder by respective ones of wireless transmitters and corresponding respective wireless receivers in a base unit. Each transmitter/receiver combination operates at a separate radio frequency to provide a zero or reference signal at a base unit and which is used to modulate a signal transmitter at the base unit. Each modulated signal, when received and demodulated provides information concerning signal sensed by a respective electrode carried by the patient, as for example, the right-leg electrode, etc.
It should be obvious from the above that it is extremely desirable to monitor a patient who is ambulatory in regard to various vital signs, such as heart rate and so on. This is even more important due to the recent trend to get patients ambulating as soon as possible. Thus, it is also important to determine the location of this patient within, for example, the confines of a hospital or other area. As one can ascertain, many modern hospitals have a great number of floors and are spread over wide areas. Since an ambulatory patient may experience a medical problem as a heart attack, the monitoring system should detect this at a central location and furthermore, receive information regarding the location of the patient within the hospital.
Thus, patients who are post-coronary or other at-risk patients should be monitored in regard to their vital signs and a position signal provided to determine the precise location of the patient within a large medical facility or some other area.
While the invention has particular applicability in determining the location of a monitored patient it is understood that the techniques described herein can be utilized for other purposes, such as for locating children in large shopping centers and so on.
It is an object of the present invention to provide both a vital sign monitoring and patient locating system which is efficient and economical. The described system enables one to monitor the vital signs and the location of the patient without requiring the patient to be provided with a separate receiving apparatus as implemented in the prior art.